Sciatica

Sciatica is pain caused when the sciatic nerve, which runs from the lower back down to the feet, is irritated or compressed. It usually affects the buttock and the back of one leg, often down to the foot and toes, as a sharp or burning pain with pins and needles, numbness or weakness. It can be worse when you move, sneeze or cough. Back pain may come with it but is usually milder than the leg pain, and if you only have back pain, it probably isn’t sciatica (NHS).

What causes sciatica?

Something presses on or rubs against the nerve. The NHS lists these causes (NHS):

• a slipped disc (herniated disc), the most common cause, which becomes more likely with age
• spinal stenosis, a narrowing of the part of the spine the nerves pass through
• spondylolisthesis, where one of the vertebrae slips out of position
• a back injury

When the problem is at a nerve root in the spine, doctors also call it lumbar radiculopathy. Less often, the nerve may be irritated in the buttock, where it passes next to the piriformis muscle, although how often that happens is not known (Hopayian & Danielyan, 2018).

Herniated discs often shrink on their own. A systematic review of studies that scanned people twice while they were treated without surgery found that sequestrated discs regressed in 96% of cases and extruded discs in 70%, while protrusions (41%) and bulges (13%) regressed less often (Chiu et al., 2015).

How common is sciatica?

Nobody can give one reliable number. A review of 23 studies found estimates ranging from 1.2% to 43%, mostly because studies defined sciatica differently and only two examined people in person. The same review notes that sciatica tends to be more persistent and severe than back pain alone (Konstantinou & Dunn, 2008).

Does sitting at a desk cause sciatica?

That has not been shown. The clearest long-term data come from four Finnish cohorts with 34,589 people followed for 12 to 30 years, using hospital admissions for sciatica as the outcome (Shiri et al., 2017):

• Current smoking raised the risk of admission by 33%, and obesity by 36%.
• Walking or cycling to work lowered it by 33%, regardless of body weight.

These are observational findings about severe cases, but they fit the NHS advice for preventing sciatica from coming back: stay active and exercise regularly, sit correctly when using a computer, keep to a healthy weight and don’t smoke (NHS). For the desk itself, see lower back pain from sitting and microbreaks.

How long does sciatica last, and what helps?

Sciatica usually gets better in a few weeks to a few months, though it can last longer and can come back (NHS).

• Keep moving. The NHS advises carrying on with normal activities as much as possible and not sitting or lying down for long periods: moving may hurt, but it isn’t harmful (NHS). A Cochrane review found little or no difference in pain or function for sciatica between advice to rest in bed and advice to stay active (Dahm et al., 2010), so bed rest brings no advantage. Whether walking helps is covered in Is walking good for back pain?
• Exercise and physiotherapy are among the main treatments the NHS lists (NHS). Stretches for the area are shown on lower back stretches.
• Medicines. NICE advises against gabapentinoids, other anti-epileptic drugs, oral steroids and benzodiazepines for sciatica, because there is no overall evidence of benefit and there is evidence of harm, and against opioids for long-lasting sciatica (NICE).
• When pain is severe. NICE suggests considering an epidural injection for acute, severe sciatica, and surgery when non-surgical treatment has not helped and the scan matches the symptoms (NICE).

When to see a doctor

See a GP if the pain has not improved after a few weeks of home treatment, is getting worse or is stopping you doing your normal activities. Go to A&E or call 999 if you have sciatica on both sides, weakness or numbness in both legs that is severe or getting worse, numbness around or under your genitals or around your bottom, or you find it hard to start peeing, can’t pee, can’t control when you pee or poo, or don’t notice when you need to poo, and this is not normal for you. Don’t drive yourself to A&E (NHS). More in red flags.